KR20180054671A - Peristaltic pump - Google Patents

Abstract

A rotor (4); Wherein the track assembly 10 is spaced from the rotor 4 to receive n tubes 12 therebetween wherein n = 2 m and m is a positive integer ≥ 2, Are manifolded together at the discharge port; One of the rotor (4) and the track (10) comprises a blocking surface for each of said n tubes; Wherein the occlusion surfaces are located at n different angular positions and the angular eccentricity between the occlusal surfaces offset the pulsation associated with each tube (12) to reduce the overall pulsation at the discharge port. do.

Description

Peristaltic pump

The present invention relates to peristaltic pumps, and more particularly, but not exclusively, to peristaltic pumps having an arrangement for reducing pulsation.

In a peristaltic pump, the pumped fluid contacts only the bore of the tube, thereby eliminating the risk of a pump contaminating the fluid. Therefore, peristaltic pumps are often used to pump sterilized fluids and therefore find application in the biopharmaceutical industry in particular.

In a peristaltic pump, the compressible tube is squeezed between the roller and a circular arc track, creating a seal at the point of contact. As the roller advances along the tube, the seal also advances. After the roller has passed, the tube returns to its original shape and creates a partial vacuum that is filled with the fluid aspirated from the suction port.

Before the roller reaches the end of the track, the second roller compresses the tube at the beginning of the track to isolate the packet of fluid between the compression points. As the first roller leaves the trajectory, the second roller continues to advance and exits the fluid through the discharge port of the pump. At the same time, a new partial vacuum is created behind the second roller, from which more fluid is drawn from the suction port.

The fluid discharged by the peristaltic pump exhibits characteristic pulsations at the pressure generated by the pumping method. Some applications are sensitive to pulsating fluid flow, so steps can be taken to reduce pulsation. For example, the pulsation amplitudes can be reduced using two channels that are in phase with each other and are manifolded to each other on the discharge side of the pump. This can be accomplished using a rotor with two eccentric sections or a pair of eccentric tracks. This is known to deliver purely reduced pulse amplitude and increased pulse frequency only at system pressures of up to 2 bar. With a system pressure of 2-4 bar, the pulse amplitude increases significantly and it is very difficult to control below 0.5 bar without additional system pulsation attenuation devices.

Therefore, it is necessary to provide a peristaltic pump having improved pulsation characteristics.

According to one aspect of the present invention, there is provided a rotor comprising: a rotor; A track assembly spaced from the rotor to receive n tubes therebetween, wherein n = 2m and m is a positive integer > = 2, the tubes being manifolded with each other at the discharge port; One of the rotor and the track assembly including an occlusion surface for each of the n tubes; The occlusion surfaces are located at n different angular positions and angular eccentricity between the occlusal surfaces offset pulsations associated with each tube to reduce overall pulsation at the discharge port.

The n tubes may include m pairs of tubes, each of the tubes in the pair having substantially the same diameter, and at least two of the pairs of tubes having different diameters.

The pairs of tubes may be interleaved with respect to a pair of small tubes and a pair of large tubes with angular positions of corresponding closing surfaces.

The angle eccentric [theta] between each occlusal surface may be substantially equal to v / n, where v is the swept volume of the occlusion surface.

The track assembly may include n track sections each defining one of the occlusal surfaces, the track sections being angularly eccentric to each other.

The rotor may include a plurality of rollers.

Reference will now be made, by way of example, to the accompanying drawings, in order to provide a better understanding of the invention and to show how it may be carried out therein,
1 is a perspective view of a pump head of a peristaltic pump according to an embodiment of the present invention;
Figure 2 is a graph of release pressure versus time for a single large channel;
Figure 3 is a graph of release pressure versus time for two large, out-of-phase channels;
Figure 4 is a graph of release pressure versus time for two small, out-of-phase channels; And
5 is a graph of the resulting emission pressure versus time for two large and two small phase different channels.

Fig. 1 shows a pump head 2 according to an embodiment of the present invention. The pump head includes a rotor 4 rotatably mounted in a pump head body (not shown). The rotor 4 has a central shaft (not shown) and three cylindrical rollers 6 extending between a pair of end caps 8. The central shaft is located at the center of the end caps 8 and the rollers 6 are eccentric from the central shaft in the radial direction but parallel thereto. The rollers 6 are each provided at the same radial distance from the central shaft, but are eccentric to each other in the circumferential direction. Specifically, the rollers 6 are eccentric by 120 DEG with respect to each other so as to be uniformly spaced in the circumferential direction.

At least one of the end caps 8 has a drive portion that can be connected to a complementary portion (e.g., a splined or keyed shaft) of a drive unit for rotating the rotor 4 about a central shaft do. The rollers 6 are rotatably mounted on the end caps 8 by ball bearings and are rotatable about the end caps 8 about their longitudinal axes.

The pump head 2 further comprises a track assembly comprising four arcuate tracks 10a, 10b, 10c, 10d (collectively referred to as tracks 10). The tracks 10 are axially spaced along the length of the rotor 4 between the end caps 8. The tracks (10) extend partially around the circumference of the rotor (4). In particular, the tracks 10 each have an arc of 120 degrees. Thus, the length of the tracks 10 corresponds to the distance (displacement) of the rollers 6. The tracks 10 are eccentric to each other. Specifically, with respect to the track 10a (at 0 占), the track 10b is eccentric by 60 占, the track 10c is eccentric by 30 占 and the track 10d is eccentric by 90 占, The tracks 10 extend around an arc of 210 [deg.]. Therefore, each track 10 is eccentric from all other tracks 10.

The track assembly is provided as part of a cover section (not shown) of the pump head 2. The cover section is separable from the pump head body and rotor 4 so that the tracks 10 can be spaced from the roller 6.

Four compressible tubes 12a, 12b, 12c and 12d (collectively referred to as tubes 12) are arranged between the tracks 10a, 10b, 10c and 10d and the rollers 6, respectively. The tubes 12 are connected to the manifold 12 upstream and downstream (the suction side and the discharge side of the pump) of the rotor 4 such that the pump head 2 has a single suction port (inlet) and a single discharge port (outlet) (Not shown).

Although not shown, the tubes 12 and manifolds can be supplied as a unified cartridge that keeps the tubes 12 in place and assists in the installation of the tube 12, thereby preventing the tubes from twisting or twisting have. The cartridge can seal the tube within a flexible (polymer) membrane to receive any particles (debris) from the tubes 12, which can enter the processing region. The cartridge may be C-shaped with a profile matching the 210 arc of tracks 10. The cartridge may be resiliently flexible to allow it to be received over the rotor 4. [ Alternatively, the cartridge may be formed as two hinged (or detachable) portions that can be locked in place after installation. In certain applications, particularly in biopharmaceutical applications, cartridges can be single-use disposable items that are discarded after a single use or use period. The cartridge can protect the tube during the gamma irradiation cycle and enable the integration of additional items such as pressure transducers and RFID tags.

Rotation of the rotor 4 causes the tubes 12 to be sequentially occluded between the rollers 6 and the tracks 10. In particular, the rotation of the rotor 4 (counterclockwise as viewed in Figure 1) causes the tubes 12a to be compressed against the track 12a by one of the rollers 6, ) And forcibly feeds the pumped fluid along the tube in the downstream direction (assuming it has already been primed). As the rotor 4 is rotated by an additional 30 °, the same roller 6 compresses the tube 12c against the track 10c. An additional rotation of 30 DEG (total 60 DEG) then causes the same roller 6 to compress the tube 12b against the track 10b and an additional rotation of 30 DEG (total 90 DEG) Allowing the tube 12d to compress against the track 10d. At a rotation of 120 degrees, the roller 6 releases the tube so that the tube 12a is compressed by the next roller 6, which starts to priming the tube 12a.

At the discharge port, it will be seen that the pulses from each tube 12 overlap. Each eccentricity of the tracks 10 causes the pulses to be out of phase, so that the pulses interfere destructively, thereby reducing the amplitude of the pulsation.

In the illustrated example, the tubes 12a, 12b have a first, larger diameter, and the tubes 12c, 12d have a second, smaller diameter. Therefore, the large-diameter tubes 12a and 12b are eccentric by 60 ° with each other, and the small-diameter tubes 12c and 12d are eccentric by 60 ° with respect to each other. It has been found that the combination of small and large diameter tubes is particularly effective in reducing the amplitude of the pulsation.

Figure 2 shows the discharge pressure for a single large diameter tube 12 and shows the pulsation tightened in a single channel pump. In contrast, FIG. 3 shows the discharge pressure for two large diameter tubes 12 that are out of phase by 60 degrees (note that the top sketch shows the pulsation of a similar pump for comparison purposes). The resulting pulsation is higher at the frequency (which may be perceived as explaining the lower pulsation), but does not significantly reduce the amplitude of the pulsation. According to Fig. 3, Fig. 4 shows the discharge pressure for two small diameter tubes 12 which are out of phase by 60 degrees. Compared to larger tubes, smaller tubes show higher frequencies, but show smaller amplitude pulses. Figure 5 shows the discharge pressure for the pump head 2 described with reference to Figure 1 comprising two large tubes and two small tubes which can be regarded as the overlap of Figures 3 and 4. As shown, the addition of low amplitude pulses from the small tubes significantly reduces the amplitude of the pulsation originating from the large tube. This combination was found to provide a ripple amplitude of +/- 0.1 bar at a discharge pressure of 4 bar (RMS).

It will be appreciated that the concepts previously described can be extended to pumps having different numbers of rollers and different numbers of channels.

For example, the rotors 4 may have four rollers 6 spaced 90 [deg.] Apart from each other. In this case, the tracks also have an arc of 90 [deg.]. In order to attenuate the high frequency pulsations generated by the four roller rotors, the angular eccentricity between the respective tracks 10 is reduced. Specifically, for a pump with displacement v, the angle eccentricity? Between each track can be defined as? =? / N, where n is the number of channels (i.e., tubes). Therefore, for four roller rotors having 90 deg. Displacement and four channels, the eccentricity between each track 10 will be set at 22.5 deg.. The positioning of the track 10 may have an associated tolerance of < RTI ID = 0.0 > 5 < / RTI > such that the angles deviate slightly from those specified above.

If necessary, additional channels may also be used. However, an even number of channels (i. E., N = 2m, where m is a positive integer > = 2) should be used to achieve the attenuation effect described above. If different sized tubes are used, these should be paired with the angular eccentricity of 2 [theta]. Therefore, for a 6-channel pump having an exhaust amount of 120 [deg.], Pairs of tubes 12 of the same diameter must be eccentric to each other by 40 [deg.]. Tubes of equal diameter should be provided in pairs or in multiples of two. Therefore, for a six channel pump, it is necessary to use three different sized tubes.

The tubes 12 and their respective tracks 10 can be rearranged from that shown and described. For example, the small and large tubes may be interleaved.

Although the pump is described as having an eccentric track, it will be appreciated that the same effect can be achieved using a rotor with eccentric lobes.

The present invention is not limited to the embodiments described herein, but may be modified or adapted without departing from the scope of the present invention.

Claims (7)

As peristaltic pumps,
Rotor:
A track assembly spaced from the rotor to receive n tubes therebetween, wherein n = 2m and m is a positive integer > = 2, the tubes being manifolded with each other at the discharge port;
One of the rotor and the track assembly including a blocking surface for each of the n tubes;
Wherein the occlusion surfaces are located at n different angular positions and angular eccentricity between the occlusal surfaces offset the pulsation associated with each tube to reduce overall pulsation at the discharge port. 2. The peristaltic pump of claim 1, wherein the n tubes comprise m pairs of tubes, each of the tubes in the pair having substantially the same diameter, and at least two of the pairs of tubes having different diameters. 3. The peristaltic pump of claim 2, wherein the pairs of tubes are capable of mutual positioning of angular positions of corresponding occlusion surfaces with respect to a pair of small tubes and a pair of large tubes. 4. A peristaltic pump according to any one of claims 1 to 3, wherein the angular offset (?) Between each occlusion surface can be substantially equal to v / n, where v is the displacement of the occluding surface. 5. The peristaltic pump as claimed in any one of claims 1 to 4, wherein the track assembly comprises n track sections each defining one of the occluding surfaces, the track sections being angularly eccentric to each other. 6. The peristaltic pump according to any one of claims 1 to 5, wherein the rotor comprises a plurality of rollers. A peristaltic pump as described with reference to the accompanying drawings and as shown in the accompanying drawings.

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